Academics and Research / News

Professor’s patent checks big rig emissions

A truck passes through University of Denver professor Donald Stedman’s experiments in testing emissions at the Port of Los Angeles. Photo: Courtesy Donald Stedman

For four decades, University of Denver chemistry professor Donald Stedman has collected, analyzed and categorized just about everything that comes out of passenger vehicle tailpipes.

He’s logged tens of thousands of emissions samples from every manner of car, motorcycle and small truck as they whizzed by his ever-present emission detection tools along Denver highways, sporting big signs with smiling cars telling drivers if their cars are running cleanly and “$aving You Money.”

And he’s developed a range of inventions from a window shade cleaner to a “nickel carbonyl detector.” But his latest patent tackles the next big thing: tractor-trailers.

Motorists may be used to the big rigs emitting columns of tar-black smoke from shiny silver smokestacks, but it doesn’t have to be that way. Stedman says with today’s engine technologies, the only trucks pumping that much soot into the air are either badly maintained or operated by drivers who simply cheat the system.

“Modern trucks, properly maintained, shouldn’t smoke,” he says.

Over a five-year period Stedman developed a practical, unobtrusive method of accurately testing big rig emissions. At a checkpoint, drivers would stop their rigs and then proceed under a canopy equipped with collection tubes at smokestack level. Drivers would be required to accelerate so as to reach a stopping point by a defined time. That would provide an accurate sample of the vehicle under normal load. Instant analysis by use of existing technologies could alert workers at the test’s endpoint if the vehicle is properly tuned and if it should be allowed to continue on.

The total test should take less than 30 seconds, Stedman says.

It’s that accurate, fast, practical measurement that makes his invention perfect for areas where governments are concerned about high amounts of soot and other harmful chemicals in the air. It could be especially handy near U.S.-Mexico border crossings, where despite the North American Free Trade Agreement, Mexican trucks are still not allowed more than 20 miles inside the United States, in part due to concerns over Mexican truck emissions not meeting American standards.

A diagram submitted with his patent for a new system of testing the emissions of 18-wheelers. Courtesy Donald Stedman

Stedman’s team worked on his big rig tester in partnership with Environmental Systems Products, the folks who test tailpipe emissions for the state along Colorado roadways. Early on, his crew erected scaffolding to help Los Angeles officials measure emissions from the aging fleet of trucks serving the Port of Los Angeles. Aware of these high emissions, government leaders used a combination of incentives and punishments to push operators to upgrade the fleet at the port. Testing in just a couple of years showed a dramatic decrease in noxious emissions there. In some cases, the tests even found some drivers were using dirty Mexican fuels that are illegal in this country.

In the Dallas-Fort Worth area of Texas, the North Central Texas Council of Governments (NCTCOG) is grappling with emissions from problem big rigs, usually older models not covered by internal monitoring devices on newer trucks.

Shannon Stevenson, program manager for air quality at NCTCOG, says her agency has reviewed Stedman’s work and is looking for a way to obtain real-world baseline emissions data on trucks to take to the state legislature when seeking reforms or emissions standards. In Texas, passenger vehicles are tested for emissions, but trucks are not. She hopes some form of testing for trucks can be in place in the next 5–10 years.

“This is an area where we really do need to start reigning in those emissions,” she says.

Her colleague in air quality operations, Jody Loza, says the big companies with large, modern fleets aren’t necessarily against testing, if it can be done quickly and without impeding travel.

Stedman’s system could be installed at places where trucks have to stop anyway, such as a border crossing or weigh station, and tests would take less than a minute.

“The biggest pushback is when we slow the trucks down, because time is money,” Loza says. “And that’s what’s really intrigued us with Dr. Stedman’s work.”

With more widespread testing, Stedman feels that one of the biggest remaining sources of vehicular pollution could be tamed, and in the process, tests at the border could ease tensions between U.S. and Mexican leaders over trucking disputes.

“I’m not a politician and I’m not interested in making money,” he says. “But I am in favor of cleaning the air. In some respects, the auto emissions problem is solved if people would buy newer cars and maintain the old ones. But trucks, no one’s solved that problem yet.”

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